[Pj]

I use a 4x40 RO system.  I struggled for about 15 months filtering from my tap pressure at 35psi into the RO, before purchasing a pressure pump.  The water goes through at 75psi now, which is great.

When I set the pressure pump up, I changed the resin and the prefilters but not the RO membrane.
After filtering through the pre-filters and RO membrane the TDS reads about 22, that's the best I can get.  So the resin is having to work hard to get it to zero.

My question is:  Do you think I may have damaged the 4x40 membrane by running water at such low pressure through it?

Anyone know?

[Pj]

yes I have thought about a softener Simon.  My tap water TDS is about 365.

Lowest I can get it after particulate filter, carbon filter, RO membrane is 20.

At this point I am just wondering if I wil need to renew the 40x4 membrane in the process.  It's only about a year and a half old.